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Description

Stubby is a 100% open source, extensible robotics platform. It features ultra low cost design (MDF frame, which you can cut with a scroll saw; $2 low torque servos; a single microcontroller; easily-obtainable electronic and mechanical components), can be controlled by a Universal Controller (over XBee) or a computer (over Bluetooth), and has a Processing API which can help children learn basic programming concepts.

My daughter, Princess Sparkle, and I have been working on it since February 2014, along with the help of some of my friends. Other hackers worldwide are working on their own versions, some of which are 3D printed, others are laser cut plexiglass, and at least one is hand cut from Baltic Beech wood for what will doubtless turn out with a beautiful, natural look.

The Universal Controller interface is completed and working, and the Processing / Bluetooth API is well underway.

Details

Since we started, Stubby has grown from a simple, direct-driven 2 DOF (degree of freedom) per leg frame to a mechanically-assisted 3 DOF per leg design with a full inverse kinematics engine (which allows the processor to calculate custom foot positions for each step, rather than relying on a static loop).

This video shows off the latest version, including various features of the Inverse Kinematics engine:

After the interesting parts (most notably the frame design and inverse kinematics engine) were completed, I wanted to expand Stubby's abilities. The Hackaday Prize made me think about 'connected' projects... at the same time, Princess Sparkle was expressing interest in computers and programming. In talking with her, we came up with the idea of making an API which would allow her to issue simple commands to control the robot.

This is not the first time she has done this sort of thing... in her Grade 1 class, there was a unit on Lego Mindstorms robots, which taught the children to visualize arithmetic expressions by programming the robot to, for instance, move 10 units forward and 3 units back, and seeing where on a number line they were (10 - 3 = 7). With Stubby, the plan is to expose more of the programming structure to her, teaching such things as procedural control, calling methods, assigning variables (by reading sensors), etc.

When finished, I plan on having an Ultrasonic Distance sensor and a magnetometer, together allowing users to write code for autonomous operation. An array of UV LEDs + photodiodes on the bottom will allow for writing line following algorithms. An i2c header is broken out, so that hackers can add completely new components as well.

For those who are interested in building their own version of Stubby, I have all the designs, plans, and theory available for all to use and modify freely. There are two documents which encapsulate the majority of my work.

First are the frame plans. The frame is one of the biggest advantages which Stubby holds over other, more expensive hexapods. The first difference is the materials: Stubby is designed to be cut from 1/4" MDF using a scroll saw. (However, the design is adaptable enough to be able to use other materials as well, and the community has modified these plans for use with a 3D printer, laser cutter, etc.) The frame is quite easy to make; simply print the plans, tape it to an 8.5x11" sheet of MDF, and cut along the lines. The second difference is how the servos are attached to the legs: Stubby uses push rods to convert distance to torque, allowing Stubby to work with cheap, low-torque servos (at the expense of being a bit more limited in leg movement). This is the biggest factor in being able to keep below $150 in components (this assumes you have no parts in your parts bin, but does assume that you have all the required tools already).

The second important diagram is the circuit board schematic. This shows how to wire the control board so that the microcontroller can perform the needed calculations and tell the servos how to move.

The hardware is useless without software to control it. You can download or browse my git repository, which includes all software, electronics, and frame design.

I have finished a preliminary version of a 'Universal Controller Emulator', written in Python. This should help those who want to play with Stubby, but cannot find a PS2 controller to re-purpose.

The program is very simple (currently about 150 lines), and is written in Python (I tested it on python 2.7 in Debian Jessie). It requires the pyserial and pygame libraries (both of which are available across all major platforms).

The controls are simple: use the keyboard to emulate the Universal Controller.

Hit 'T' to press the Start button on the UC.

Hit 'Right Control' and 'Left Control' to press the R2 and L2 buttons on the UC

Use WASD keys to emulate the left joystick

Use the arrow keys to emulate the right joystick

That's all that is implemented so far (and that is all that is currently used by Stubby). If you want to extend this program to support other keys, it would be very easy to do so.

Note that in order to get key press / release events working in a cross platform manner, I need to use pygame (and I need to open a SDL window, which in turn requires focus). It is just an empty, black window at 320x200 pixels in size. I'm not a fan of it, but it works.

You can download this program from the GitHub repository, under the 'python' folder.

I don't use Windows at all, so my workflow has always been very Linux-centric. A couple days ago, Chris emailed me with some questions about building on Windows... it turns out that there were a few problems. There were symlinks in my git repo, some filenames didn't work properly on Windows, and compilation failed with a few different problems when using the (older - released in 2010) avr-gcc for Windows.

To get things working better, I split Stubby source into its own github repository (previously, it was lumped in with all my other projects), and removed all symlinks. I fixed the code in a couple places where Windows didn't like it. However there was still the problem when compiling using avr-gcc versions older than 4.8; when you tried to do this, you would get a bunch of errors from the math libraries:

This problem is apparently quite common, and there are tons of references on how to fix it (specifically, don't use -mshort-calls option). However I was not using it. Finally I found a post on a forum which indicated that the problem is that the linker was trying to get the math functions from libgcc rather than avr-libc. The solution was to put -lc and -lm near the beginning of the compiler command, and -lc again at the end. Sure enough, it works! I have now fixed the Makefile, and things should be working on winavr as well as other older versions of avr-gcc.

To recap: to compile in Windows, you need to download the code (see the links section at the side for the Github Stubby repository), and then compile...

I am not familiar with the PS3 bluetooth protocols, but I would be very surprised if it could be made to work. It would definitely *not* work with the same HC-05 bluetooth serial link.

If you were able to get it to work, you would almost definitely need to get another Bluetooth module which could interface with the PS3 controller, create some sort of interface using a separate microcontroller which translates the PS3 commands into serial data, and then passes it over the serial link to the main AVR.

In short, it is likely not possible, and even if it was possible it would be a lot of work.

I'm very happy to see a walking robot here that was developed from zero, and it's fun to see how your designs progressed. I had very similar experiences with my quadruped several months ago (except that I never even dreamed about making a special PCB for it). I can't wait to see what it can do apart from being a remote controlled toy -- when you actually get to designing the behaviors for it. It's very cool to be able to control a crawler like this, but it's even more fun to make it "alive" by making it react to its surroundings.

There are really two types of IK, though. The main one that I talk about is the leg IK. This lets me position each foot in X,Y,Z co-ordinate space. The roll and pitch could probably be considered 'body IK'. To do this, I take the X,Y,Z positions of each foot, and run them through a mathematical function which applies a rotation in 3D space. (Specifically, we are doing a 'rotational matrix' in linear algebra... and don't ask me to explain how it works, because I forgot most of my linear algebra stuff years ago). The axis of rotation determines whether we are doing pitch, roll, or a combination of the two. The code which actually does the rotation is in stubby/source/util/Point.cpp (function rotate2D), and is called from multiple places, including stubby/source/controllers/universal_controller.c around line 102.

I'm curious on why you are using a self hosted git repository instead of a
popular "social" coding service like GitHub. This would make people able to
easily contribute with pull requests.
For example I'm planning on making a variant of Stubby using mbed based ST
Nucleo boards http://developer.mbed.org/platforms/?tvend=10If I get enough time to make it work I would like to share the code for other
people to try. :-)

I actually was talking about how you were going to physically connect the servos. You need a high current rail for VBAT and GND to supply enough power to each servo. On the Stubby board I use 50mil traces. Just curious how you are planning that if you are not making some sort of adaptor board.

I'm trying to convert the frame .dxf file to an .svg file ready for an online laser cutting service. Problem is there are many "double" lines because when 2 lines appear to be shared they are not really shared, just a line on top of another. This is bad because 1) it almost doubles the price and 2) having the laser cut 2 times on the same line could probably produce a worst result on the cuts.
How can I fix this problem? I could manually fix the exported .svg file but it doesn't like the cleanest solution to me. I'm not familiar with CAD applications, maybe there is some kind of functionality to address problems like this. Could you think of another solution?

In the past I have found some of these duplicate lines and cleaned them up as I find them... however from what you are saying, I must not have found them all. Are there tons of them, or are you finding them only in a few places? If the former... I guess I need to go through everything again and see if I can find them all. If the latter, let me know what parts they are in, and I will look to clean them up.

(Each part is an 'object', which is then copied multiple times, so this task is not as daunting as it may seem... for instance, even though there are 12 femur parts, in reality it is just one that has multiple instances.)

Ahh... or are you talking about the main section where I have lined up parts to be beside each other? If that is the case, what is the best way to address it? Should I separate each part, such that there is room in between each part? I have never used a laser cutting service, so I don't know what the optimal output is; the blueprint where the parts are up against each other was created like that for cutting with a scroll saw, for which it definitely makes sense.

I'm talking about the file frame_3dof_radial.dxf. http://www.pasteall.org/pic/show.php?id=78599 look at this image, I made it exporting the .dxf to .svg. As you can see there are lines really close to each other where there could be just one. A laser cutting service move the laser on top of every line it will find and it will not understand that cutting multiple times on the same path is useless so it will do double work.
At the same time putting space between each part would throw a good optimization away: you designed the parts to share the paths, as a matter of fact this is really good for 3d laser cutting as you can make the process a lot cheaper.

OK, I see what you mean. I assume that this is due to one of two issues:
1) I did not align the parts properly when designing it. That is definitely a possibility, although I generally used the 'auto aligning' mode of QCad when moving parts, which should have minimized this.
2) The SVG export is at fault.

I'll take a look and see if I can figure out what is happening, and post back here.

The perfect alignment will not prevent the machine from seeing two different
lines: imagine just two segments perfectly on top of each other going from x=2,
y=5 to x=2, y=10, when reading the file the machine will see a sequence of
commands like "enable laser from (2, 5) to (2, 10); enable laser from (2, 5) to
(2, 10);". It will just do the cut twice, even if it pointless.
Some details on how to avoid this kind of behavior with Inkscape:
http://support.ponoko.com/entries/20736451-Avoid-doubled-up-blue-cutting-lines-in-your-designsI'm trying to adjust the design but it is my first time with CAD software, I
will post the (poor) result as soon as I am done.

That is a bit more difficult... since each part is an object (duplicated
multiple times), there will be double lines on the edges. To change this, you
would have to convert everything back to being lines / curves (rather than being
grouped into an object), and delete the redundant ones. I don't know of an
automatic way of doing this. I am somewhat surprised that there is not a way to
do this automatically when converting to gcode (or whatever the laser cutter
requires)... you would think that it is a common problem.

Regardless, long-term I definitely want to keep each part as its own object. This allows me to edit something one time and have the change applied to all identical parts. Likewise, I can move each part around as a unit.

Perhaps there is an option for this in your .dxf to .svg conversion software?

The .dxf to .svg conversion software is QCAD (trial binary version). I agree about the manual conversion/editing: it is not a clean solution. That is why I asked here, hoping for some kind of automatic functionality in the CAD itself.

OK, gotcha. I just downloaded the latest trial version, and tried playing around a bit, but to no avail... I got it exported to Inkscape nicely, but I couldn't find a way to merge the overlapping lines.

I *did* do some things that should help overall, though...
1) I moved the text, dimensions, and extra stuff (outline of PCB, etc) to their own layers; you can then hide / show these layers as desired.
2) I re-did all the drill holes to be the proper size (previously, I just used the drill holes as center markers with an approximate size, since I was using a drill bit to actually drill the holes... now, the sizes should be correct, so a laser cutter will get the right dimensions).

OK, I worked on the SVG exported version of the frame: http://uhmler.com/media/frame_3dof_radial_pre_laser_cut.svg.zipWould you please take a quick look and confirm that the design is in sync with the DXF? You pushed some commits while I was working and I am not really sure on what you changed exactly :-).
I tried to upload the design to a laser cutting service online ( http://vectorealism.com ) : cutting the whole frame on 4mm MDF is less than $20, on 5mm transparent acrylic is about $45.

Looks good for the most part... some things to note:
1) The DXF has multiple top layers, designed for the different PCBs. You currently have all three of them (the three six-sided shapes on the bottom and right, with nothing inside of them; the one with three femur pieces inside it is the bottom layer). You can (should?) remove the ones which you don't want to use, to save materials and cost. See the DXF text layer for labels saying which is which.
2) Likewise, the mount for the distance sensor does not need to be cut out unless you are mounting a distance sensor. (This mount is the strange shaped item in the top right corner, looks kind of like a space invader)
3) If you *do* want to mount the distance sensor, you will need to add the cutout for the distance sensor frame in the top body layer. If you look in the DXF, on the 'Extra' layer, you will see an indent to be cut, with a label (on the text layer) saying "Distance Sensor mounting slot". (This only exists for the rev 2 and 2.1 versions of the top layer, since rev 1 PCBs can't run a distance sensor).

Other than that, I think you are looking good. If you remove the top layers which you are not using, and optionally the distance sensor frame, you should be able to save another 30% or so of the cost.

As for what changed... while I am not sure of the exact timeframe, it looks like the commit I made was just to label the original top layer as "Rev 1 top layer". You should be fine as-is.

(BTW, sorry for the long time to reply... HaD didn't send an email notifying me to new comments. Feel free to email me directly in the future if you want to; my address is at http://stubby.digitalcave.ca .)

hello again Wyatt, Sorry to bother you again apparently setting up the Xbee S1 modules its more complicated than i expected, i hope you can give me a hand, basically, i have 2 Xbess i need to configure 1 as endpoint and the other as coordinator, however since it’s the first time I use them im a bit confused, how do I set the function sets up using the new (or old) XTCU software to only use TX and RX pins? There’s way to many functions sets and few information about the S1 modules, (there’s a lot about the S2 tho) I just haven’t been able to get around this , API mode? AT mode?, which xbee goes where?

I got your email, and tried to reply, but got an error saying that your mailbox does not exist. Oh well... the gist of my reply is that even though I wrote this Java program (since XCTU was not available on my OS), that it was actually pretty hard to get set up due to the RXTX library for serial communications. If I was running Windows (which I assume you are), it would probably be better to just use XCTU.

Hi. Thanks for a great project that indeed looks like a usefull mechanical and IK teaching "toy".
I wanted to built one myself so I got all the servos needed though I got stuck at the laser cutting of the mechanical frame.
The files itself were impossible for me to load due to either text being overlayed or the dimensions being wrong. Even with the DXF files I was unable to load them.
In which software have you designed these? Is it possible to get the original file format of this project?

I have also tried to 3D print the mechanical frame without luck as well. Here it happened to me that all the parts were to small, especially the holes for the servos were to small to fit a servo. There weren't made any space for the cable coming out of the end of the servo as well.

Great to see another open source hexapod coming. I'm new to this community and before I dig deep into Stubby, I really want to thank you for sharing all these great works. If it were me I would probably want to patent all of these and make some money out of them. You're admirable.

Great to see another open source hexapod coming. I'm new to this community and before I dig deep into Stubby, I really want to thank you for sharing all these great works. If it were me I would probably want to patent all of these and make some money out of them. You're admirable.

Maybe you could use an optical mouse with modified optics, in order to make the mouse sensor see under the hexapod instead of a usual mouse pad. That will be a good way to read the real movement path and distance.

The mouse thing is a great idea... I'll have to try pulling apart an old mouse and see what I can do with it. That would eliminate some of the 'fudge factor' I am currently using to measure distances (although once I have it set, it is actually very accurate).

1 ) I already got most of the mechanical stuff ready, i have been writing an android app to control stubby from cellphones using bluetooth modules, i have been checking out the code from the controller, and just to make sure i understand this, my app would have to send exactly these signals via bluetooth so i would have to simulate several buttons using example ( button start 0x04 ) , also , according to the code you dont seem to have used the L/R buttons is there any reason of why? (i could use them to add some laser diodes)

2) I already cloned your repos using git, At the moment im using windows and having a bit of trouble using AVR GCC and AVRDude, i currently have limited access to an AVR dragon so im planning as an emergency in case I cant find a programmer to replace it on using it to burn my micros using the compiled hex files for both the controller and stubby, would it be to much to ask if you could upload both hexfiles? so i can burn it asap before i lose access to this programmer?

3) About the new board (Blue one) and the all the bugfixes and edits at the code since the magnetometer was added, what are the chances of the code still running as intended in the 1.0 board (black one), will another revision of the board come? if not i might as well order a bunch of the blue one

4) i kind of want to make my own "stubby battle version" (yes, lasers) i have been looking for ways of putting even more weight down by replacing the eneloop batteries by some Lipo batteries, you seem to have worked with quad copters before , so i wanted your advice, in short how possible would it be to buy a 5v 20,000mAh batteries that weight less than the eneloops
5) just to be creepy I want to add a way of transmission of digital voice communication into stubby, example, using a mic placed in the controller and send the signal via xbee to stubby in order for it to replicate my voice 10m away from me using a speaker, (reason of why I need more battery power), I have been trying to find a way to accomplish this without altering that much the original circuit, but I still have to find a wait to doinig, im not sure this is possible using the BT modules but I believe it could be possible using the Xbees , I would like to know if you have any advice or documentation regarding this , before I start doing this,

Thanks for your time to answer the questions and all your effort into the project , im learning a lot just by trying to do what you have accomplished until know,

1) Correct. Stubby currently uses a multi byte protocol to send / receive messages. The protocol is described in doc/protocol.txt. As for what messages you send, you have a few options there:
a) Emulate the Universal Controller messages
b) Emulate the Processing API messages
c) Implement your own controller (this is not nearly as hard as it sounds!)

Option b) would likewise give you access to everything the Processing API can do. As of today, that includes move a specified distance and turn to the specified angle, but more is being added daily.

Option c) would give you full control of what you can do. If you wanted to add a freakin' laser to Stubby's head, this is the way to do it. To do this, you would probably be best off to copy controllers/processing.*, call it "controllers/android" or something, and implement whatever features you want. If you do go this route let me know, and I can reserve a block of messages for the Android API use (for instance, messages in the range 0x00 - 0x0F are common to everything, 0x10 - 0x1F are for Universal Controller, 0x20 - 0x2F are for Processing API, 0x30 - 0x3F are for the (work in progress) Python Calibration program).

2) Send me an email (my email is on http://stubby.digitalcave.ca) and I can get you the current hex files. Keep in mind that this is very much a work in progress, and that things are changing daily, so if you can get a programmer, that would be best long-term. I bought a usbTinyISP from Adafruit a few years back and am loving it.

About the avr-gcc troubles... I found that it works best using version 4.8.1 (I have done it on Debian Jessie and Mac OSX using Crosspack. I don't have any Windows machines, so unfortunately I can't offer any suggestions there.

3) I currently have 3 (or maybe 4, depending on how you look at it) versions of the board:

-Rev 1.0 is the first one I ordered, and is what I am using now. It runs the microcontroller at 3.3v (and so is limited to about 12MHz). It is through hole with some larger SMD components, and can be soldered by hand with an iron (that's how I did it).

-Rev 1.1 (semi official) is identical to Rev 1.0 but with holes for a few capacitors added to help smooth power. I have not printed any of these, but I think that a few people who have printed their own have it.

-Rev 2.0 features a complete redesign of the power supply. The microcontroller runs at 5v (and so can be run at 20MHz), but there is still a 3.3v supply for peripherals. This board uses mostly SMD components, many of which are very small. I would not want to solder this one by hand with an iron; as soon as the boards arrive (I am hoping it will be this week), I plan on soldering it using a reflow method, with solder paste and a heat gun. To add a magnetometer, you will need to use an external one (I ordered one from Adafruit for $10, and it is working perfectly on my Rev 1.0 board)

-Rev 2.1 is a minor redesign of 2.0, and has a magnetometer on board. I have not ordered it yet, and have no immediate plans to do so. If I progress into the finals, this will be the board that would be used for a 'product' version.

Now, the obvious question at this point is which board to use? My suggestion is to consider whether you want to use a distance sensor or not, and whether you are comfortable doing fine pitch SMD soldering or not. The distance sensor is the only thing which cannot work on rev 1.x boards, since it requires a 5v supply. I plan on supporting all board revisions in the future (using #defines in the code), so there should be no problem with any of them.

4) I am not aware of any batteries which fit your specifications. LiPos do not come in 5v (they have a nominal voltage of 3.3v - 3.6v / cell, which means that a 1 cell battery is not nearly enough to power the servos, and a 2 cell battery is too high voltage and will damage the servos. If you are going to use a LiPo, you would need a regulator circuit as well, to regulate the voltage down to something between 4.8v - 6v. Linear regulators (i.e. 7806 (6v) or 7805 (5v)) could potentially work, but you would need to gang a few of them together to achieve the current needed for 18 servos, and you may not get great life out of the batteries since you need a couple of volts over the rated output. Plus, being a linear regulator, there would be a lot of wasted power (as heat). The alternative would be some sort of step down regulator, but max current is also a concern there.

In short, I am not aware of any better options than AA's at the moment, although I am keeping my eyes open for options.

5) That sounds like fun! :-) I have not tried transmitting audio over XBee or Bluetooth, (I have only used the serial ports on either of those), so unfortunately I can't help with this question at all. Sorry!

No it is not done with an Arduino; but it does use the same CPU family as Arduino does (the Atmel ATMega family of chips). A normal Arduino does not have enough pins to do what is required (drive 22 PWM signals), and the Arduino IDE is far too inefficient to do everything which needs to be done in real time.

Hello Wyatt and the Stubby team,
it looks like you've not updated the project in a couple of weeks. Now is the time to check and edit your project documentation on Hackaday Projects to give Stubby the best chance of going through to the next round of The Hackaday Prize.

I think you've got most of it covered, but this is the checklist of what must be on Hackaday Projects by August 20th:
- A video (check)
- At least 4 Project Logs (definitely check)
- A system design document. You have a lot of design docs. It would be great if you could highlight the main ones in the project Details.
- Links to code repositories, and remember to mention any licenses or permissions needed for your project. For example, if you are using software libraries you need to document that information in the project details.

Thanks for the tips, Jasmine! I have updated the project details with the two most important diagrams (frame design and control board schematics), and duplicated the links from the links section describing the repository and what is included, and clarified the licensing.

Hard to say when I started I had electronics experience but no robotics experience. 6 months later I had stubby. I would say that if you are patient and willing to make mistakes it would be very doable. Email me and I will help how I can. Everyone has to start somewhere and here is as good a place as any.

I'd love to build one - a little beefier, can be controlled via a cellphone app or PC, has a camera mounted on it. I have no idea how to do these things so that would be a nice learning experience. Do you think you'd sell them as kits? I have almost no access to the required parts - especially the PCB and the frame :/

I have some pcbs left and have been sending them to a few people. Send me an email with your address and I can let you know the cost.

The frame would be a bit harder as I cut it by hand and it takes a very long time. Someone has posted plans for a 3d printed frame which you could try out. Anyway email me and we can chat. My aemail is on my digitalcave website.

Hello Wyatt thanks for all the help, and for keeping updated your log and project page,

I already got most of the components already, i just have to find the xbee modules you used since i have never used radio communication modules before reason of why im a bit confused, i will get 2 for both the PS2 controller and stubby, wherever i look (mostly ebay) i find way to many versions of the xbee, and the breakout board, some are way to expensive others are not, im a bit confused about which one is it, could you point me out in the right one please?

I had some XBee Pro version 1 modules from a previous project. There are a few things to note when choosing this:

1) Make sure you get Series 1, not Series 2. They are different, and not compatible. (Series 2 may be fine, but I have no experience with it and cannot say for certain)
2) XBee Pro have a much longer range than normal XBee. Long range is probably not required for this project, so you can go with the cheaper modules unless you think you may be re-using them for other stuff.
3) I think that these ones should work fine: http://www.digikey.ca/product-detail/en/XB24-AWI-001/XB24-AWI-001-ND/935965 . However, the ones I used are: http://www.digikey.ca/product-detail/en/XBP24-AWI-001/XBP24-AWI-001-ND/9359684) Since you don't already have any RF stuff (i.e. no legacy requirements), you could really use anything that gives you a transparent serial port and runs at 3.3v. Basically, the interface Stubby is expecting is to be able to send data over the serial port. whatever radio you pick, it only needs to transparently send data which it receives over the serial port. For instance, I am working on using Bluetooth SPP modules for this (will be controlled by the computer).

Wyatt, I have several questions regarding your project which im already in the process to replicate and if possible to improve in order to learn something more, Here come a bunch of newbie questions, please brace yourself for my ignorance

1.- What exactly which servos did you use?, I found this “$2” 9g servos in hobby king,

Assuming I replace the top of the frame with some modified MDF roof in order to make it able to carry stuff around while it moves (Increasing the weight) would higher weight servos accomplish this?

3.- This one is just to make sure I understand how to use a Xbee, if the PS2 controller has been modified like yours , I will need another module of the Xbee placed into stubby, , module, Stubby will need another one right however since I don't have a model at hand ?

4.- I have programed PICs 18F… using a pickit2, however I wanted to ask you exactly which programmer and what software did you use in order to program the AVR pic

5.- At the component list for stubby “1x Control PCB” can be found however I find this confusing

6.- Any chance you post some pictures of the assembled and soldered PCB and the connection with the Xbee?

7.- What software did you use to make the MDF designs? i tried using Corel, Ilustrator and Autocad to open them and review them with no luck until now, they do open but all messed up

8.- I just noticed you just updated the Assembly Instructions in your project page, they are very detailed, great job Any chance we can get some high resolution pictures?

2) If you wanted it to carry anything substantial (anything more than 25g or so - it is already borderline as far as weight is concerned), I would definitely want to use larger servos. The problem with that is that larger servos will not fit in the frame I designed, so you would have to modify it. Now, this is not very hard, but would involve using a CAD program (I used QCad and can highly recommend it), and that may have a bit of a learning curve if you have not used a CAD program in the past. More specifically, the coxa servos should be fine as they are, with the smaller servos (there is not a lot of load placed on these ones), The servos driving the femur and tibia should be larger, though.

3) Correct, you need two XBees to communicate with each other. The design really only calls for some sort of serial communication, though, so you could use any module that provides serial communication at 3.3v. I am planning on putting one of those cheap serial Bluetooth modules on Stubby sometime (in which case you would control it with the computer). Other options could include various eBay serial modules, or even just a cable for testing. You would probably have to tweak the software a bit, as right now it is relying on the protocol from my Universal Controller, but that is not a big deal.

4) I am using LadyAda's USBTinyISP programmer (http://www.adafruit.com/products/46). The software is AVR-GCC (compiler) and AVRDude (to upload programs). I have no idea how to get this installed in Windows, but on Debian it is easy (install avr-libc and avrdude) and on Mac I just use Crosspack (http://www.obdev.at/products/crosspack/index.html). I know you can do it on Windows, I just don't know how. To compile everything, clone the git repo, go to projects/stubby/source and type 'make'. To install, 'make install'. To set the fuses on the AVR, 'make fuse'. You can verify that you have everything installed properly before buying a single item, by trying 'make program'. It will fail to upload, of course, but the error should be from avrdude saying the programmer is not found, rather than from the OS saying avrdude is not found.

5) The control board is a PCB which I have designed and ordered from DirtyPCBs.com (the design looks like http://static.projects.hackaday.com/images/4964341397760277202.png). I have a few extra which I can send via letter mail for $5 if you are in the USA ($4 for Canada, a bit more for international depending on the country in question). This board uses a lot of surface mount resistors and capacitors, but is solderable using a normal soldering iron as long as you have steady hands. Look for Youtube videos on how to solder 0603 SMD components by hand. Alternatively, you can wire up everything by hand using a protoboard and through hole components according to the schematics (this is what I used at first, while still designing the circuit). The schematic is at http://stubby.digitalcave.ca/stubby/schematics.jsp.

7) I used QCad for the frame design. I don't have access to any of those other programs, so have no idea how compatible they are.

8) Which pictures do you want higher resolution versions of? I kept them small to conserve bandwidth on my site (and since most of those pictures don't really need great detail, as they are just showing how things attach together), but I could link to some higher resolution ones if needed. Just let me know...

(Strictly speaking, you only need one of the three capacitors: the one which filters between GND and 3v3. If you don't have this one, the AVR will brown out when all the servos are moving at the same time. However, you could use the original design and just solder a cap on the expansion port, where I have already broken out GND, 3v3, VBAT, and A0-A2: this is what I have done.) I have the caps marked as 2200uF for the two capacitors on VBAT, and 470uF for the one on 3v3, although I am probably going to use a 2200uF one for all three. Currently I have a 470uF on 3v3 and that works, but larger wouldn't really hurt for something like this.

As to which one you should choose, that is really up to you. The original one is guaranteed to be correct, since it is the one which I had ordered. The new one should be fine, and has the advantage of some more capacitor holes, but I have not tried it myself.

Regardless of which one you choose, I would recommend uploading to a gerber viewing site (I use http://www.gerber-viewer.com/) and verify that things look right. (Look for things like holes not matching the solder mask, etc).

Finally, depending on where you are located, it may be easier / cheaper / faster for me to send you one of my boards. (You get 10 per order, and I only needed a couple). This would probably cost about $4 or $5 for one board, depending on exactly where you are located. Email me if you are interested. (Offer open to anyone pending interest and availability... first come, first served).